Because of the recent energy crisis, many home dwellers are becoming more reliant upon fireplaces to heat their homes, at least partially, during the winter months.
Existing fireplaces are capable of heating a room into which the fireplace opens to a reasonable extent, but most fireplaces "pull" draft air from the room into which the fireplace opens with the result that the air for supporting combustion within the fireplace and drawn into the latter must be replaced within the associated building. Accordingly, a slight negative pressure is generated by a fire burning within a fireplace and this negative pressure draws replacement air into the associated building through the many small passages through which air from the exterior of a building may pass into the interior thereof with the result that rooms distant from the room into which the fireplace opens become cooled by the air entering the building structure from the exterior thereof to replace the air "pulled" into the fireplace for draft purposes.
Although some fireplaces are equipped with exterior draft air ducts and some of these fireplaces include glass doors to prevent or substantially reduce the movement of air from within the associated building structure into the fireplace, fireplaces equipped with glass doors do not radiate as much heat into the associated room.
While a few fireplaces equipped with outside draft air ducts also include built-in heat exchanger structure within the fireplace, and thus increase the amount of heat available for heating the interior of the associated building, a need still exists for a more efficient manner of preventing ambient air from entering the interior of a building through the many small passages through which air from the exterior of a building may pass into the interior thereof. Also, even a fireplace with heat exchanger structure and glass doors exhausts a considerable amount of heat to the exterior of the associated building through the flue pipe thereof.
Examples of various forms of fireplace heat exchanger structures including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 311,313, 553,750, 2,277,381, 2,348,834, 2,361,644, 2,481,861 and 3,724,443. However, these previously known structures are not as efficient as they could be for the purpose of providing maximum heat to the interior of an associated building while burning a minimum amount of fuel.